This invention relates generally to portable electric room air heaters and particularly to upright radiant heaters suitable for placement in a corner or any other location in a room while occupying a minimum amount of floor space. As will become apparent to those familiar with the art, aspects of this invention may be used with other types of heaters.
An upright or so-called "tower" heater is relatively tall in relation to its horizontal area or "footprint." Examples are shown in U.S. Design Pat. No. 111,000, granted Aug. 23, 1938, to C. Knox et al., and U.S. Design Pat. No. 141,834 granted to W. E. Maxson, Jr. on Jul. 10, 1945. These may be contrasted to horizontal heaters that have a relatively low profile, such as shown in U.S. Pat. No. 3,175,550, issued to R. S. Knapp on Mar. 30, 1965, U.S. Pat. No. 3,059,090, granted to R. S. Waters on Oct. 16, 1962, and U.S. Pat. No. 3,610,882, issued to William A. Omohundra on Oct. 5, 1971.
One of the problems encountered in any portable heater is the creation of localized "hot spots" on or adjacent the heater. These are areas that get much hotter than adjacent areas. Hot spots are undesirable because they can present a fire hazard as well as cause discomfort to the user of a heater. Portable electric air heaters sold in the United States at this time must meet testing requirements of Underwriter's Laboratories, Inc. when in actual service, so that the heaters do not present a risk of fire, electric shock or personal injury when operated continuously under abnormal conditions. With many heaters, such tests can only be passed successfully by the use of relatively expensive safety control devices.